• The Journal of Korea Robotics Society
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• v.15 no.4
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• pp.323-329
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• 2020

This paper presents a control algorithm for a wearable walking aid robot for subjects with paraplegia after stroke. After a stroke, a slow, asymmetrical and unstable gait pattern is observed in a number of patients. In many cases, one leg can move in a relatively normal pattern, while the other leg is dysfunctional due to paralysis. We have adopted the so-called assist-as-needed control that encourages the patient to walk as much as possible while the robot assists as necessary to create the gait motion of the paralyzed leg. A virtual wall was implemented for the assist-as-needed control. A position based admittance controller was applied in the swing phase to follow human intentions for both the normal and paralyzed legs. A position controller was applied in the stance phase for both legs. A power controller was applied to obtain stable performance in that the output power of the system was delimited during the sample interval. In order to verify the proposed control algorithm, we performed a simulation with 1-DOF leg models. The preliminary results have shown that the control algorithm can follow human intentions during the swing phase by providing as much assistance as needed. In addition, the virtual wall effectively guided the paralyzed leg with stable force display.

• Korean Journal of Applied Biomechanics
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• v.30 no.4
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• pp.293-299
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• 2020

Objective: The aim of this study was to investigate the swing and aerial motion of Kovacs, and evaluate the skill level of Kovacs by Korean adult players on horizontal bar. Method: The subjects for this study were 6 male top athletes participated in the 46th National Gymnastics against Cities and Provinces. After the motions of Kovacs were filmed by digital highspeed camcorder setting in 90 frames/s, kinematical data were calculated through DLT method. The variables were computed in the lapse time, the joint angle, the position·velocity of body COG, the inferred tension force of bar, and body COG path were simulated according to skill level of Kovacs. Results: Firstly, it was revealed that the lapse time was 1.19±0.03 s in the swing phase, and 0.83±0.03 s in the aerial phase. Secondly, it was revealed that the shoulder·hip joint motions of S1 and S2 were better than the other subjects in the swing phase, and the knee joint motions of S1 and S2 were better than the other subjects in the aerial phase. Thirdly, it was revealed that the horizontal·vertical velocity of body COG were -1.40±0.03 m/s, 3.80±0.07 m/s respectively, and the vertical positions of S1 and S2 were higher a little than the other subjects. Lastly, the skill level of Kovacs of this subjects was evaluated into 3 steps; excellent, advanced, normal. They need to train the swing motion including a giant circle, and body motions in the air. Conclusion: It would be suggested that Korean domestic players should improve to increase the vertical velocity at release instant and train to control the limbs elaborately in the air.

• Journal of Magnetics
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• v.20 no.2
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• pp.129-132
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• 2015

The aim of the present study was to examine whether repetitive transcranial magnetic stimulation (rTMS) can improve gait ability of acute stage stroke patients. This study was conducted with 39 subjects who were diagnosed as having a hemiparesis due to stroke. The experimental group included 20 subjects who underwent repetitive transcranial magnetic stimulation and the control group included 19 subjects who underwent sham therapy. The stroke patients in the experimental group underwent conventional rehabilitation therapy and rTMS was applied daily to the hotspot of the lesional hemisphere. The stroke patients in the control group underwent sham rTMS and conventional rehabilitation therapy. Participants in both groups received therapy five days per week for four weeks. Temporospatial gait characteristics, such as stance phase, swing phase, step length in affected side, velocity, and cadence, were assessed before and after the four week therapy period. A significant difference was observed in post-treatment gains for the step length in the affected side, velocity, and cadence between the experimental group and control group ( p < 0.05). However, no significant differences were observed between the two groups on stance phase and swing phase ( p > 0.05). We conclude that rTMS may be beneficial in improving the effects of acute stage stroke on gait ability.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.8
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• pp.814-823
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• 2011

Nowadays many neurological diseases such as stroke and Parkinson diseases are continually increasing. Orthotic devices as well as exoskeletons have been widely developed for supporting movement assistance and therapy of patients. Robotic knee orthosis can compensate stiff-knee gait of the paralyzed limb and can provide patients consistent assistance at wearable environments. With keeping a robotic orthosis wearable, however, it is not easy to develop a compact and safe actuator with fast rotation and high torque for consistent supports of patients during walking. In this paper, we propose a novel kinematic model for a robotic knee orthosis to drive a knee joint with independent actuation during swing and stance phases, which can allow an actuator with fast rotation to control swing motions and an actuator with high torque to control stance motions, respectively. The suggested kinematic model is composed of a hamstring device with a slide-crank mechanism, a quadriceps device with five-bar/six-bar links, and a patella device for knee covering. The quadriceps device operates in five-bar links with 2-dof motions during swing phase and is changed to six-bar links during stance phase by the contact motion to the patella device. The hamstring device operates in a slider-crank mechanism for entire gait cycle. The kinematics and velocity/force relations are analyzed for the quadriceps and hamstring devices. Finally, the adequate actuators for the suggested kinematic model are designed based on normal gait requirements. The suggested kinematic model will allow a robotic knee orthosis to use compact and light actuators with full support during walking.

• Korean Journal of Applied Biomechanics
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• v.26 no.2
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• pp.191-195
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• 2016

Purpose: The purpose of this study was to analyze the immediate effects of ankle restriction with an elastic band on ground reaction force during a golf swing. Method: There were five subjects who were teaching pros with an average golf score of 75. A force platform (9281B, Switzerland) was used. The independent variable was the presence of an elastic band. The dependent variables were three-dimensional ground reaction forces to analyze the transfer of momentum with the timing, control and coordination of the three forces. A paired t-test within subject repeated measure design was used via an SPSS 20.0. Results: Wearing an elastic band around one's ankles significantly makes shorter time differences between the moment of cross anterior / posterior forces and vertical force and median value of anterior / posterior forces during the backswing, between medial and lateral maximum and anterior / posterior force from the top of the back swing to the mid down swing, and creates an anterior / posterior maximum force. Conclusion: Wearing an elastic band around one's ankles affects control and coordination between three dimensional forces, and anterior force power according to each phase of the golf swing.

• Korean Journal of Applied Biomechanics
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• v.21 no.3
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• pp.345-352
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• 2011

The purpose of this study was to determine how spandex wear with compressive band affects biomechanical parameters during a golf swing. Nine male golf players, each with at least 6 years golf experienc(handy 4.5${\pm}$5.4), were recruited as the participants. Eight pairs of surface electrodes were attached to the left and right side of the body to monitor the pectoralis major(PM), external abdominal oblique(AO), erector spinae(ES), and vastus lateralis(VL). This study showed that the angular velocity of the club in EG were increased during the down swing phase but X-Factor and X-factor Stretch were reduced. Average and maximum nEMG (normalized EMG) values of the left AO(external abdominal oblique) were less in EG(experimental group) compared with CG(control group) during the back swing, whereas those of left PM(pectoralis major) in EG were greater than CG. It is more likely that EG performed effectively golf swing without excess muscle activity. Thus, the spandex wear with compressive band played an important role in improving swing performance with injury prevention. This has led to suggestions of the need for further kinetic and kinematic analyses to evaluate its function.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.5
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• pp.407-412
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• 2015

This paper presents the design of a lab-built powered knee prosthesis based on a BLDC motor, a sensored impedance control using a force sensor, and a sensorless impedance control through torque estimation. Firstly, we describe the structure of the lab-built powered knee prosthesis and its limitations. Secondly, we decompose the gait cycle into five stages and apply the position-based impedance control for the powered knee prosthesis. Thirdly, we perform an experiment for the torque estimation and the sensorless impedance control of the prosthesis. The experimental results show that we can use the torque estimation to control the low impedance during the swing phase, although the estimated torque data has a delay compared with the measured torque by a load cell.

• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.167-177
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• 2009

The purpose of this study was to investigate effect of golf shoe design on kinematic variables during golf swing. Five professional male golfers with shoe size 270mm were recruited for the study. Swing motion was collected using 8 high speed camera motion analysis at a sampling of 180Hz. Kinematic variables were calculated by EVaRT 4.2 software. Driver swing was divided into four events; El(adress), E2(top), E3(impact) and E4(finish). Time, peak velocity, velocity of center of mass, velocity of the foot and ankle angle during Phase 1(El-E2), Phase 2(E2-E3), and Phase 3(E3-E4) were analyzed in order to investigate the relationship between golf shoe design and swing performance. The findings indicated that type C golf shoes would be beneficial for stability and control of movement during address and swing performance. Furthermore, faster speed of golf shoes, center of mass, and both feet were observed with Type C golf shoes. It is expected that golfers with Type C golf Shoes provide greater force as they control the center of mass faster and increase rotational force during impact compared to other golf shoes.

• The Journal of Korean Physical Therapy
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• v.34 no.3
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• pp.98-103
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• 2022

Purpose: New therapeutic approaches have emerged to improve gait ability in patients with brain damage, such as action observation learning (AOT), auditory cueing, motor imagery etc. We attempted to investigate the effects of AOT with auditory cueing (AOTAC) on gait function in patients with stroke. Methods: The eighteen stroke patients with a unilateral hemiparesis were randomly divided into three groups; the AOTAC, AOT, and control groups. The AOTAC group (n=8) received training via observing a video that showed normal gait with sound of footsteps as an auditory cue; the AOT group (n=6) receive action observation without auditory stimulation; the control group (n=5) observed the landscape video image. Intervention time of three groups was 30 minutes per day, five times a week, for four weeks. Gait parameters, such as cadence, velocity, stride length, stance phase, and swing phase were collected in all patients before and after each training session. Results: Significant differences were observed among the three groups with respect to the parameters, such as cadence, velocity, stride length, and stance/swing phase. Post-hoc analysis indicated that the AOTAC group had a greater significant change in all of parameters, compared with the AOT and control groups. Conclusion: Our findings suggest that AOTAC may be an effective therapeutic approach to improve gait symmetry and function in patients with stroke. We believe that this effect is attributable to the change of cortical excitability on motor related to cortical areas.

• The Journal of Korean Physical Therapy
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• v.30 no.1
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• pp.14-22
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• 2018

Purpose: This study examined the effects of the lower limb alignment on the pelvis, hip, and knee kinematics in people with genu varum during stair walking. Methods: Forty subjects were enrolled in this study. People who had intercondylar distance ${\geq}4cm$ were classified in the genu varum group, and people who had intercondylar distance <4cm and intermalleolar distance <4cm were placed in the control group. 3D motion analysis was used to collect the pelvis, hip, and knee kinematic data while subjects were walking stairs with three steps. Results: During stair ascent, the genu varum group had decreased pelvic lateral tilt and hip adduction at the early stance phase and decreased pelvic lateral tilt at the swing phase compared to the control group. At the same time, they had decreased minimal hip adduction ROM at the early stance and decreased maximum pelvic lateral tilt ROM and minimum hip rotation ROM at the swing phase. During stair descent, the genu varum group had decreased pelvic lateral tilt at the early stance and decreased pelvic lateral tilt and pelvic rotation at the swing phase. In addition, they had decreased pelvic frontal ROM during single limb support and increased knee sagittal ROM during the whole gait cycle. Conclusion: This study suggests that a genu varum deformity could affect the pelvis, hip and knee kinematics. In addition, the biomechanical risk factors that could result in the articular impairments by the excessive loads from lower limb malalignment were identified.